The present invention relates to seat belt devices for protecting automobile passengers during collisions, and more particularly, to an air belt device having a bag-like portion, which is inflated by gas generated by a gas generator.
More particularly, the present invention relates to an air belt device having a bag-like shoulder belt and a vertically movable gas generator installed at one end of the shoulder belt.
Japanese Unexamined Patent Publication No. 5-112200 describes a prior air belt device. A perspective view of the air belt device is shown in FIG. 12(a). A cross-sectional view of the air belt device taken along line B--B in FIG. 12(a) is shown in FIG. 12(b).
As shown in the drawings, an air belt device 1 extends from the right side of a passenger. The device 1 includes a shoulder belt 2, a seat belt retractor 3, a lap belt 4, a buckle 5, a tongue 6, a belt guide 7, a gas generator 8, and an adjustor 9. One end of the lap belt 4 is connected to the shoulder belt 2. The other end of lap belt 4 is connected to the seat belt retractor 3, which is an emergency locking retractor (ELR), to wind and retract the lap belt 4. The seat belt retractor 3 and the buckle 5 are arranged on opposite sides of a seat and arranged on the vehicle floor, or the like. The tongue 6 slides freely along the lap belt 4 and is engaged with the buckle 5 when fastening the seat belt. The belt guide 7 is secured to a body pillar, or the like, to guide the shoulder belt 2. The shoulder belt 2 is further connected to the gas generator 8. The gas generator 8 is actuated during emergency situations, such as when a collision occurs, to generate a gas product, which is drawn into the bag-like shoulder belt 2. The adjustor 9 adjusts the vertical position of the gas generator 8.
The shoulder belt 2 has a belt body 2c. The belt body 2c, for example, may be folded and covered by a cover 2d. The sides of the cover 2d are sewed to each other such that a stitching 2e is formed. This keeps the shoulder belt 2 in a strip-like state under normal situations.
The adjustor 9 has a vertically extending ball screw 9a, to which the gas generator 9a is screwed, and a motor 9b for rotating the ball screw 9a. When the motor 9b rotates the ball screw 9a, the gas generator 8 moves vertically in accordance with the rotating direction of the ball screw 9a. In other words, the end of the shoulder belt 2 connected to the gas generator 8 is moved vertically to adjust the shoulder belt 2 in accordance with the size of the passenger's body.
The above air belt device is kept in a strip-like state under normal situations.
The passenger sits on the seat and fastens the belt by inserting the tongue 6 into the buckle 5. If the length of the shoulder belt 2 and the lap 4 is inappropriate for the passenger, the motor 9b of the adjustor 9 is driven to move the gas generator 8 vertically and adjust the length of the belts 2, 4 to fit the passenger.
When a collision occurs, the gas generator 8 is actuated to generate gas and inflate the shoulder belt 2.
The inflated shoulder belt 2 holds the passenger and securely protects the passenger from great impact loads. Furthermore, the slack of the shoulder belt 2 is absorbed during the inflation. This enhances the passenger constraining force of the belt.
Japanese Unexamined Patent Publication No. 5-85301 describes an air belt device having a webbing connected to the bag-like shoulder belt. A shoulder belt retractor winds and retracts the webbing. Gas is drawn into the bag-like shoulder belt through a gas passage extending through the tongue and buckle. A gas generator is incorporated in the buckle. When the gas generator is actuated with the tongue and buckle in an engaged state, gas flows through the gas passage and enters the shoulder belt.
In the air bag device of Japanese Unexamined Patent Publication No. 5-112200, the gas generator 8 is connected to one end of the shoulder belt 2. This allows the adjustor 9, which includes the ball screw 9a and motor 9b, to adjust the vertical position of the gas generator 8. Due to this structure, the tension applied to the shoulder belt 2 lacks elasticity. Thus, the passenger may feel uncomfortable when fastening the seat belt. In other words, when a passenger tries to move his body, the shoulder belt 2, which is connected to the adjustor 9, constrains the passenger.
In the air bag device of Japanese Unexamined Patent Publication No. 5-85301, the webbing is connected to one end of the shoulder belt. The retractor winds and retracts the webbing. Thus, if the passenger tries to move his body, the webbing is pulled and extended from the retractor. This allows the passenger to move his body with ease. However, this air bag device requires a gas passage to be formed in the tongue and buckle. In addition, gas must be drawn into the shoulder belt without the gas leaking out of the joint between the fastened tongue and buckle. As a result, the structure of the tongue and the buckle is complicated.